<!DOCTYPE html>
<html>
<head>
	<title></title>
</head>
<body>

<script type="text/javascript">
	
let map = new Map();
map.set("first", "hello");
map.set("second", "world");

for (let [key, value] of map) {
	console.error(key + " is " + value);
}

console.error("--------------------------");

for (let [key] of map) {
	console.error("key = " + key);
}

console.error("--------------------------");

for (let [, value] of map) {
	console.error("value = " + value);
}

</script>

</body>
</html>